Revert "cmdline: add scheduler interface"

This reverts commit 2e78a5c702e5f95416d9686a50a7431ae3b7b6ff.
Deadline i/o scheduler - added morfic's 1:1 secret sauce that I remember
back from the Iconia A500 days.

Conflicts:
	block/deadline-iosched.c
block: recursive merge requests

In my workload, thread 1 accesses a, a+2, ..., thread 2 accesses a+1,
a+3,.... When the requests are flushed to queue, a and a+1 are merged
to (a, a+1), a+2 and a+3 too to (a+2, a+3), but (a, a+1) and (a+2, a+3)
aren't merged.
With recursive merge below, the workload throughput gets improved 20%
and context switch drops 60%.
Signed-off-by: Shaohua Li <shaohua.li@intel.com>
block: Adding ROW scheduling algorithm

This patch adds the implementation of a new scheduling algorithm - ROW.
The policy of this algorithm is to prioritize READ requests over WRITE
as much as possible without starving the WRITE requests.

Change-Id: I4ed52ea21d43b0e7c0769b2599779a3d3869c519
Signed-off-by: Tatyana Brokhman <tlinder@codeaurora.org>

*Squashed commit from CodeAurora for ROW scheduler.
**Backported from 3.4 version.
block: Add support for reinsert a dispatched req

Add support for reinserting a dispatched request back to the
scheduler's internal data structures.
This capability is used by the device driver when it chooses to
interrupt the current request transmission and execute another (more
urgent) pending request. For example: interrupting long write in order
to handle pending read. The device driver re-inserts the
remaining write request back to the scheduler, to be rescheduled
for transmission later on.

Add API for verifying whether the current scheduler
supports reinserting requests mechanism. If reinsert mechanism isn't
supported by the scheduler, this code path will never be activated.

Signed-off-by: Tatyana Brokhman <tlinder@codeaurora.org>

Conflicts:

	include/linux/elevator.h
block: Add API for urgent request handling

This patch add support in block & elevator layers for handling
urgent requests. The decision if a request is urgent or not is taken
by the scheduler. Urgent request notification is passed to the underlying
block device driver (eMMC for example). Block device driver may decide to
interrupt the currently running low priority request to serve the new
urgent request. By doing so READ latency is greatly reduced in read&write
collision scenarios.

Note that if the current scheduler doesn't implement the urgent request
mechanism, this code path is never activated.

Signed-off-by: Tatyana Brokhman <tlinder@codeaurora.org>

Conflicts:

	include/linux/elevator.h
row: Adding support for reinsert already dispatched req

Add support for reinserting already dispatched request back to the
schedulers internal data structures.
The request will be reinserted back to the queue (head) it was
dispatched from as if it was never dispatched.

Signed-off-by: Tatyana Brokhman <tlinder@codeaurora.org>
row: Add support for urgent request handling

This patch add support for handling urgent requests.
ROW queue can be marked as "urgent". If an urgent queue was
un-served in a previous dispatch cycle and a request was added
to it - it will trigger issuing urgent request to the device driver.

Signed-off-by: Tatyana Brokhman <tlinder@codeaurora.org>
block: fixes required to make the kernel compile with ROW.

Signed-off-by: franciscofranco <franciscofranco.1990@gmail.com>
Block: use a freezable workqueue for disk-event polling

commit 62d3c5439c534b0e6c653fc63e6d8c67be3a57b1 upstream.

This patch (as1519) fixes a bug in the block layer's disk-events
polling.  The polling is done by a work routine queued on the
system_nrt_wq workqueue.  Since that workqueue isn't freezable, the
polling continues even in the middle of a system sleep transition.

Obviously, polling a suspended drive for media changes and such isn't
a good thing to do; in the case of USB mass-storage devices it can
lead to real problems requiring device resets and even re-enumeration.

The patch fixes things by creating a new system-wide, non-reentrant,
freezable workqueue and using it for disk-events polling.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Acked-by: Tejun Heo <tj@kernel.org>
Acked-by: Rafael J. Wysocki <rjw@sisk.pl>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
block: row: Add some debug information on ROW queues

1. Add a counter for number of requests on queue.
2. Add function to print queues status (number requests
   currently on queue and number of already dispatched requests
   in current dispatch cycle).

Change-Id: I1e98b9ca33853e6e6a8ddc53240f6cd6981e6024
Signed-off-by: Tatyana Brokhman <tlinder@codeaurora.org>
block: row: Insert dispatch_quantum into struct row_queue

There is really no point in keeping the dispatch quantum
of a queue outside of it. By inserting it to the row_queue
structure we spare extra level in accessing it.

Change-Id: Ic77571818b643e71f9aafbb2ca93d0a92158b199
Signed-off-by: Tatyana Brokhman <tlinder@codeaurora.org>
block: row: fix sysfs functions - idle_time conversion

idle_time was updated to be stored in msec instead of jiffies.
So there is no need to convert the value when reading from user or
displaying the value to him.

Change-Id: I58e074b204e90a90536d32199ac668112966e9cf
Signed-off-by: Tatyana Brokhman <tlinder@codeaurora.org>
block: row: Aggregate row_queue parameters to one structure

Each ROW queues has several parameters which default values are defined
in separate arrays. This patch aggregates all default values into one
array.
The values in question are:
 - is idling enabled for the queue
 - queue quantum
 - can the queue notify on urgent request

Change-Id: I3821b0a042542295069b340406a16b1000873ec6
Signed-off-by: Tatyana Brokhman <tlinder@codeaurora.org>
block: cfq: tweak all CFQ tunables. Researched by my mates malaroth, osm0sis, joaquinf, The Gingerbread Man, pkgnex, Khrushy, shreddintyres. Please if you copy this values make sure you cherry-pick it properly and leave these guys in the commit message, they researched this for a long time.

Signed-off-by: Francisco Franco <franciscofranco.1990@gmail.com>
block: cfq: finally nailed CFQ tunables correctly, damn multipliers. Thanks osm0sis for cranking this last bit up.

Signed-off-by: Francisco Franco <franciscofranco.1990@gmail.com>
block: deadline: hardcode values
based on values courtesy of franco

Conflicts:
	block/deadline-iosched.c
block: cfq: winning values.

Signed-off-by: Francisco Franco <franciscofranco.1990@gmail.com>
block: deadline: rework
franco's way is easier for the long run, even if there's no functional difference.

Conflicts:
	block/deadline-iosched.c
[PATCH 1/4] block: prepare I/O context code for BFQ-v6r2 for 3.1

Conflicts:
	block/Kconfig.iosched